Q756. Do I need to calculate the moisture content of the methane emitted from my coal mine?

A756. If the volumetric flow rate and methane concentration are not measured on the same basis (one is wet and the other is dry) then you should calculate the moisture content of the methane, as explained in equation FF-1.  The conversion of percent relative humidity to moisture content is usually done with a psychrometric table or chart.  These tables and charts are typically found in science and engineering handbooks, and are now readily available on the internet as well.  We do not prescribe a particular conversion formula.  When volumetric flow rate and methane concentration are measured on the same basis (both wet or both dry), you do not need to calculate the moisture content of the methane emitted.  In this case, when calculating methane liberated from the coal mine according to equation FF-1 (40 part 98.323), the moisture correction factor is 1 and moisture content is N/A.  Any field in the reporting form for moisture content should be left blank, and any validation messages about moisture content that pop up when you are submitting your reporting form should be disregarded.